Field of the Invention
The present invention pertains to a cleanout composition and method for removing wellbore and well drilling equipment contaminants using a caustic alkyl polyglycoside solution.
Background
In the drilling and workover of oil and gas producing wells and certain types of fluid injection wells, it is necessary and desirable to clean out unwanted materials from the wellbore. For example, in the drilling and completion of an oil well, prior to perforating the casing in the formation region of interest, it is important to remove contaminants such as drilling fluids, pipe sealants/lubricants and other residues in the wellbore. Failure to perform the cleanout operation can result in contamination and plugging of the formation by the above-mentioned contaminants in the well. Wells which have already produced subterranean fluids and wells used for injection of fluids also, from time to time, require cleanup of the wellbore to remove contaminants such as hydrogen sulfide precipitates and injection water contaminants.
Although many types of surfactants have been used in wellbore cleanout processes, there is a continuing need for improved cleanout materials, in particular surfactant materials which will effectively remove the wellbore contaminants, provide for the lowest cost in relation to their performance capability, and which are preferably biodegradable and less toxic than prior art materials. It is to these ends that the present invention has been developed with a view to providing a superior surfactant formulation and method for wellbore and well drilling equipment cleaning.